It is well established that computers can communicate across local or wide area networks, the Internet and wireless networks. Internet Protocol (IP) provides a hierarchical, hardware-independent addressing system for delivering data and communications between computers and other devices on a routed network. Each network adapter that is present in a computer or other device in a TCP/IP network has a unique IP address, where an IP header in data packets transmitted in the network include source and destination address information.
Multicasting is the delivery of information to a group of devices on the network simultaneously, where only those devices intended to receive a specified multicast transmission (e.g., by monitoring the multicast packet address header) accept the multicast transmission. Those devices on the network not intended to receive the multicast transmission discard it when received. By comparison with multicast transmissions, conventional point-to-point delivery between two devices is referred to unicast transmission.
A one-to-many or many-to-many Internet Protocol (IP) application involves one or multiple sources sending IP messages to multiple receivers. Exemplary applications include the transmission of corporate messages to employees, communication of stock quotes to brokers, video and audio conferencing for remote meetings and telecommuting, remote training, content-on-demand and providing web site information. IP multicast protocol efficiently supports one-to-many or many-to-many applications by allowing a source to send a single copy of a message to multiple receivers. IP multicast is more efficient than a point-to-point unicast protocol that requires the source to send an individual copy of a message to each receiver separately, thereby limiting the number of receivers by the bandwidth available to the sender. IP multicast is also more efficient than a broadcast protocol that sends one copy of a message to every node on the network even though many of the nodes may not want the message. IP multicast protocol is applicable not only to wired networks, but also wireless networks. For example, in wireless network, link level multicasting allows several terminals to receive data sent over a single air interface.
It is also well known that satellite receivers and transmitters can be used to transfer high volumes of digital data over a network. Satellite transmissions provide an efficient medium for communicating multicast transmissions through an air interface to multiple receivers or sites throughout a geographical area at the same time. Inherent to that advantage is that all receivers within the footprint or range of the satellite transmissions can receive such transmissions. There is thus a need to provide secure, encrypted multicast transmissions over satellite communications to only allow those receivers intended to receive the multicast transmission access to underlying content in the multicast transmission and prevent unauthorized receivers from accessing the underlying content.
Internet Protocol Security (IPSec) is an architecture and related Internet key exchange (IKE) protocol, described by IETF RFCs 2401-2409 which are hereby incorporated by reference, that provides a robust security protocol used on TCP/IP networks. IPSec provides confidentiality, access control, authentication, data integrity and replay protection services for IP level communications. IPSec provides the benefit of encryption-based security to any network application, regardless of whether the application is security-aware. However, IPSec requires the protocol stacks of both source and destination devices to support IPSec. IPSec uses a number of encryption algorithms and key distribution techniques that are dependent upon unicast point-to-point transmissions between two devices. While IPSec is ideal for providing security between network devices, such as routers, the required unicast transmission prevents the IPSec protocol from being implemented to encrypt multicast satellite transmissions being sent to multiple receivers.
Prior attempts to secure multicast satellite transmissions required using specialized scrambling algorithms and hardware at the receiver to decrypt encrypted multicast satellite transmissions, such as the common scrambling algorithm (DVB-CSA) and common interface (DVB-CI) used in Digital Video Broadcasting (DVB). These prior attempts also required the incoming transmission to be decrypted as it was received and did not allow the multicast satellite transmissions to be forwarded on in their encrypted state. There is clearly a need to overcome these and other limitations in the prior art by providing a system and method for utilizing IPSec protocol to encrypt multicast communications.